1. Field of the Invention
The present invention relates to a photothermal actuator, which is used for a guide wire, a catheter, and an endoscope etc.
2. Description of the Related Art
In the industrial field, an endoscope is used for checking or inspecting areas where a human can not enter (for example inside a gas tube) or narrow spaces which define a plurality of curved surfaces etc. In the medical field, an endoscope and a catheter are used for diagnosing and treating internal organs in order not to seriously harm the human body.
Recently, medical technology has been advancing. With these advances, diagnosis and treatment using catheters and endoscopes has been increasing. In this type of diagnosis and treatment, the catheter and the endoscope have to reach the affected area in the body through a complex path such as a meandering vein.
Therefore, conventionally the catheter and the endoscope are bent by an actuator having a shape memory alloy coil as shown in Japanese Unexamined Patent Publication (KOKAI) NO.08-299447. Further, as shown in Japanese Unexamined Patent Publication (KOKAI) NO.09-79204, conventionally the catheter and the endoscope are bent by an actuator using a fluid pressure.
However, these actuators have complex structures. Therefore, they are difficult to miniaturize. Further, when a shape memory alloy coil is used, an electric current is sent to the actuator in the human body for heating the coil of the actuator. In this situation, the electric current has to be controlled carefully. Furthermore, when using fluid pressure, the fluid pressure has to be controlled carefully too.